地震研究

通过对2011年3月10日盈江5.8级地震近场区水位、气汞等前兆观测资料的分析,发现该地震前震中附近区域的前兆观测异常较为显著,2010年初异常开始出现,7月后异常数量显著增加,盈江5.8级地震前1个月前兆异常出现转折、异常数量开始减少; 怒江断裂以西的震中附近地区异常以水位升高和气汞浓度增加为主,显示震区附近地区受到挤压,孔隙压力增加的应力状态; 短临阶段异常由外围向震中迁移的特征可作为地点预测的参考依据。最后对近场异常从机理上进行了初步的探讨。

Analyzing the precursory observation data of water level and gas mercury in near field before Yingjiang M_S5.8 earthquake on Mar. 10,2011,we found that the precursory anomaly was obvious in the area within 200 km range from the epicenter. The precursory anomaly appeared in early 2010,and the number of precursory anomaly items increased from Jul.,2010,however it decreased and the precursory anomaly appeared turning in one month before Yingjiang M_S5.8 earthquake. The rising of water level and increasing of gas mercury concentration were the main precursory anomaly in the area near the epicenter in the west of Nujiang Fault,which showed that the area near the epicenter in extrusion leaded to the stress state of increasing of pore pressure. The characteristic of the short-term and impending anomalies was the migration from the periphery to the epicenter,which could be taken as the reference of epicenter location prediction. Finally,the mechanism of the near-field anomalies was preliminary discussed.

引言
1 震区地质构造与前兆台网分布
2 前兆观测异常
3 前兆时间演化特征及异常机理讨论
4 结论

图1 1976年以来滇西地区M≥5地震震源机制解和前兆监测台网分布图<br/>Fig.1 Distribution of focal mechanism solutions of M≥5 earthquakes form 1976 and precursory monitoring network

图1 1976年以来滇西地区M≥5地震震源机制解和前兆监测台网分布图
Fig.1 Distribution of focal mechanism solutions of M≥5 earthquakes form 1976 and precursory monitoring network

图2 腾冲(a)和施甸台(b)水位五日均值(曲线)与月降水雨量(柱状)时间进程图<br/>Fig.2 Diagram of water level curve of 5-day mean value and monthly rainfall bar graph of Tengchong(a)and Shidian(b)Stations

图2 腾冲(a)和施甸台(b)水位五日均值(曲线)与月降水雨量(柱状)时间进程图
Fig.2 Diagram of water level curve of 5-day mean value and monthly rainfall bar graph of Tengchong(a)and Shidian(b)Stations

表1 腾冲、施甸水位峰值与年降雨量统计表<br/>Tab.1 Statistics of peak value of water level and annual rainfall at Tengchong and Shidian Stations

表1 腾冲、施甸水位峰值与年降雨量统计表
Tab.1 Statistics of peak value of water level and annual rainfall at Tengchong and Shidian Stations

图3 施甸水位峰值与年降雨量关系图<br/>Fig.3 Relationship between peak value of water level and annual rainfall at Shidian Station

图3 施甸水位峰值与年降雨量关系图
Fig.3 Relationship between peak value of water level and annual rainfall at Shidian Station

图4 芒市水位旬距平值(a)、旬均值、年降雨量(b)<br/>Fig.4 Diagram of ten days departure(a),ten days mean value and annual rainfall(b)at Mangshi Station

图4 芒市水位旬距平值(a)、旬均值、年降雨量(b)
Fig.4 Diagram of ten days departure(a),ten days mean value and annual rainfall(b)at Mangshi Station

图5 滇西水位观测井分布(a)及2011年盈江5.8级地震前水位异常空间等值线(b)<br/>Fig.5 Distribution of water level observation stations in western Yunnan(a)and spatial isograms of water level anomalies before Yingjiang MS5.8 earthquake in 2011(b)

图5 滇西水位观测井分布(a)及2011年盈江5.8级地震前水位异常空间等值线(b)
Fig.5 Distribution of water level observation stations in western Yunnan(a)and spatial isograms of water level anomalies before Yingjiang MS5.8 earthquake in 2011(b)

图6 盈江5.8级地震前腾冲台(a)、芒市台(b)、盈江台(c)气汞异常示意图<br/>Fig.6 Gas mercury anomalies at Tengchong(a),Mangshi(b)and Yingjiang(c)Stations before Yingjiang MS5.8 earthquake

图6 盈江5.8级地震前腾冲台(a)、芒市台(b)、盈江台(c)气汞异常示意图
Fig.6 Gas mercury anomalies at Tengchong(a),Mangshi(b)and Yingjiang(c)Stations before Yingjiang MS5.8 earthquake

图7 盈江5.8级地震前气汞异常空间迁移图<br/>Fig.7 Spatial transferring map of gas mercury anomalies before Yingjiang MS5.8 earthquake

图7 盈江5.8级地震前气汞异常空间迁移图
Fig.7 Spatial transferring map of gas mercury anomalies before Yingjiang MS5.8 earthquake

图8 腾冲宏观异常点分布图<br/>Fig.8 Distribution of macroscopic anomalies points in Tengchong

图8 腾冲宏观异常点分布图
Fig.8 Distribution of macroscopic anomalies points in Tengchong

表2 腾冲宏观异常统计表<br/>Tab.2 Macroscopic anomalies statistic in Tengchong

表2 腾冲宏观异常统计表
Tab.2 Macroscopic anomalies statistic in Tengchong

图9 盈江5.8级地震前兆异常项数变化图<br/>Fig.9 Numbers of precursory anomalies items before Yingjiang MS5.8 earthquake

图9 盈江5.8级地震前兆异常项数变化图
Fig.9 Numbers of precursory anomalies items before Yingjiang MS5.8 earthquake

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备注

引言

1 震区地质构造与前兆台网分布

2 前兆观测异常

3 前兆时间演化特征及异常机理讨论

4 结论

期刊信息